"Iwa-bukuro" (Penstemon frutescens) belongs to Scrophulariaceae (the Figwort family). It is a perennial herb that is distributed northward from northern Honshu to Hokkaido of Japan, as well as the Kuril Islands and North East Asia. This herb grows on alpine rocky places or screes, and can reach 2-15 cm in height. The stem is quadrangular. The leaves are ovate-elliptic, thick, serrate and arranged in opposite. The pale purple, two labiate flowers bloom from July to August. The flowering clusters and calyces are covered thickly with glandular, white hairs.